1. Field of the Art
This invention relates generally to endoscopes in use in medical fields, and more particularly to an expandable anchor mechanism for use in a so-called biopsy channel in an endoscopic insertion rod or the like, for the purpose of tentatively holding fore end portions of an inserted bioptic or surgical treating instrument in a stably fixed state during a treatment.
2. Prior Art
As well known in the art, endoscopes are largely constituted by a manipulating head assembly, an insertion rod to be introduced into a body cavity of patient, and a universal cable which is disconnectibly connected to a light source or other external unit. In this regard, FIG. 16 shows layout of the manipulating head and connected parts typical of medical endoscopes in general.
In that figure, indicated at 1 is a manipulating head assembly, at 2 an insertion rod, and at 3 a universal cable. As seen in FIG. 17, the insertion rod 2 is provided with an angle section 2b between a rigid distal end section 2a and an elongated flexible rod section 2c which is flexible in arbitrary directions and which is extended forward from the manipulating head assembly 1. Provided on an end face or on a lateral side of the distal end section 2a is an illumination window through which illumination light rays are projected toward a subject of particular interest, along with an endoscopic observation window to observe therethrough the illuminated subject. Accordingly, upon introducing the distal end portion of the insertion rod into a body cavity, one can observe, through the observation window, the images of intracavitary walls under illumination by light rays from the illumination window.
In this manner, endoscopes are used for observation of body cavities and, depending upon results of observation or examination, it permits use of various bioptic or surgical instruments such as forceps, high frequency instruments and the like, for example, for sampling tissues in a particular region of interest or for stopping bleeding. A medicinal feed tube is also often used by way of an endoscope for sending in a dose of injection medicine or for sprinkling an image enhancing pigment or coloring agent for closer and more accurate observation of a body cavity or for sending in other medicinal liquids. For these purposes, the insertion rod 2 is provided with a so-called biopsy channel 4 which is normally includes a rigid end passage 5 which is opened on a distal end face (or on a lateral side) of the rigid distal end section 2a of the endoscopic insertion rod 2, and a flexible passage 6 constituted by a flexible tube which is connected to the rigid end passage 5 at its fore end through a connector pipe 7. The flexible passage 6 is passed coextensively through the flexible section 2c of the insertion rod 2 and into the manipulating head assembly 1 of the endoscope. The proximal end of the flexible passage 6 is connected to an entrance 8 of the biopsy channel, which is provided on the manipulating head assembly 1.
In case an infected or diseased portion is spotted within a body cavity as a result of an endoscopic examination, for example, a surgical instrument like forceps or high frequency instrument could be inserted through the biopsy channel to administer an appropriate treatment to the infected portion. For example, there may be used forceps 11 with a movable operating member 10 such as a pair of pincerlike claws or the like. In this instance, the movable operating member 10 is provided at the fore end of an elongated coil tube member 12 the proximal end of which is connected to a manipulating handle 13 which is maneuverable to control movements of the operating member 10. The coil tube member 12 is required to be flexible over its entire length in order to be able to flex itself together with the flexible section 2c of the endoscopic insertion rod 2 which is bendable in arbitrary directions at the time of insertion into body cavity. Besides, the manipulating handle 13 is normally connected to the movable operating member 10 through wires and link members in such a way that the operating member 10 can be opened and closed by pulling wires back and forth in the axial direction of the insertion rod. Accordingly, the coil tube member 12 is in the form of a hollow flexible tube of a tightly wound coil internally providing a passage for the manipulating wires.
In use, the operator introduces the forceps 11 into a body cavity through the instrument entrance 8 on the manipulating head assembly 1 of the endoscope, sending the forceps 11 forward of the insertion rod 2 through the flexible passage 6 until the movable operating member 10 is protruded out of the rigid end passage 5 via the connector pipe 7. Then, after advancing the movable operating member 10 at the distal end of the forceps 11 to an aimed treating position, the operating member 10 is manipulated from the manipulating handle 13, for instance, in such a way as to remove an infected portion.
In this connection, the biopsy channel 4 on the endoscopic insertion rod 2 is designed to receive treating instruments various sizes in diameter, range from thick ones, which take the full capacity of the biopsy channel 4 in terms of diameter, to thin or narrow ones, which have an outside diameter far smaller than the inside diameter of the biopsy channel 4, more specifically, which are one half or less than one half of the inside diameter of the biopsy channel 4, depending upon the purpose or nature of the treatment to be administered. In addition, normally forceps have a bulky shape at a fore end portion with the movable operating member 10 while the coil tube member 12 is normally smaller than the movable operating member 10 in outside diameter.
Therefore, as shown particularly in FIG. 17, it is often the case that, when the forceps 11 are introduced into the biopsy channel 4, a relatively wide gap exists between the inner wall of the biopsy channel 4 and the oil tube 12, leaving the forceps 11 in an instable state. Nevertheless, the forceps 11 have to be operated by remote control from the manipulating handle 13 which is externally projected on or over the manipulating head assembly 1 of the endoscope. Besides, when opening and closing the movable operating member 10 from the manipulating handle 13, the operating force is exerted on the forceps 11 as a whole. Because of the gap space which exists between the outer periphery of the coil tube member 12 and the inner periphery of the biopsy channel 4, particularly, of the end passage 5 on the distal end section 2a of the insertion rod, difficulties are often experienced in controlling the movements of the movable operating member 10 which tends to deviate in arbitrary directions due to looseness and instability, failing to secure satisfactory targetability of the forceps toward the infected portion to be treated. On top of this problem, the targetability of the treating instrument is impaired greatly by the flexibility of the treating instrument itself, for example, the coil tube member 12 of forceps which is made of a flexible material in order to secure as high flexibility as possible from a viewpoint of ensuring resistance-free and easy movements of the instrument at the time of insertion into a body cavity.